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| author | Peter Zijlstra <peterz@infradead.org> | 2021-05-06 22:33:53 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2021-05-12 15:54:50 +0300 |
| commit | 25cf0d8aa2a3440ed32bf1f8df1310d6baf3f1e8 (patch) | |
| tree | 5dc4498dea4c98e90b87942754f16068b7161bef /tools/objtool/include | |
| parent | 6efb943b8616ec53a5e444193dccf1af9ad627b5 (diff) | |
| download | linux-25cf0d8aa2a3440ed32bf1f8df1310d6baf3f1e8.tar.xz | |
objtool: Rewrite hashtable sizing
Currently objtool has 5 hashtables and sizes them 16 or 20 bits
depending on the --vmlinux argument.
However, a single side doesn't really work well for the 5 tables,
which among them, cover 3 different uses. Also, while vmlinux is
larger, there is still a very wide difference between a defconfig and
allyesconfig build, which again isn't optimally covered by a single
size.
Another aspect is the cost of elf_hash_init(), which for large tables
dominates the runtime for small input files. It turns out that all it
does it assign NULL, something that is required when using malloc().
However, when we allocate memory using mmap(), we're guaranteed to get
zero filled pages.
Therefore, rewrite the whole thing to:
1) use more dynamic sized tables, depending on the input file,
2) avoid the need for elf_hash_init() entirely by using mmap().
This speeds up a regular kernel build (100s to 98s for
x86_64-defconfig), and potentially dramatically speeds up vmlinux
processing.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210506194157.452881700@infradead.org
Diffstat (limited to 'tools/objtool/include')
| -rw-r--r-- | tools/objtool/include/objtool/elf.h | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h index 45e5ede363b0..90082751f851 100644 --- a/tools/objtool/include/objtool/elf.h +++ b/tools/objtool/include/objtool/elf.h @@ -84,11 +84,18 @@ struct elf { bool changed; char *name; struct list_head sections; - DECLARE_HASHTABLE(symbol_hash, ELF_HASH_BITS); - DECLARE_HASHTABLE(symbol_name_hash, ELF_HASH_BITS); - DECLARE_HASHTABLE(section_hash, ELF_HASH_BITS); - DECLARE_HASHTABLE(section_name_hash, ELF_HASH_BITS); - DECLARE_HASHTABLE(reloc_hash, ELF_HASH_BITS); + + int symbol_bits; + int symbol_name_bits; + int section_bits; + int section_name_bits; + int reloc_bits; + + struct hlist_head *symbol_hash; + struct hlist_head *symbol_name_hash; + struct hlist_head *section_hash; + struct hlist_head *section_name_hash; + struct hlist_head *reloc_hash; }; #define OFFSET_STRIDE_BITS 4 |